We cannot change the sys and system password in usual way as like till 11g. we have different method to do same. following blog describe the way to change user password in oracle 12c database. How to change SYS/SYSTEM password in 12C-Oracle 12C Administration =================================================== PDB1@ORCL= alter session set container=CDB$ROOT; Session altered. PDB1@ORCL=show con_id CON_ID

—————————— 1 PDB1@ORCL= alter user SYSTEM identified by oracle container=all; User altered. PDB1@ORCL= alter session set container=pdb1; Session altered.

PDB1@ORCL= show con_id CON_ID —————————— 3